The goal of the following research is to explore the dynamics of visual processing induced by transcranial magnetic stimulation (TMS), a brain stimulating device that non-invasively focuses a magnetic field at a certain region of cortex. The focal magnetic field induces a current in underlying brain tissue, capable of generating action potentials of neurons. Previous visual studies employing TMS find multiple latencies (and several different regions) of stimulation disrupt processing of visual stimuli. Simultaneous TMS/EEG studies report a propagating wave of activity throughout the brain induced by the TMS. Experiments within this proposal attempt to understand the impact of the TMS on the visual system AND during visual processing with simultaneous TMS/EEG. This somewhat rare pairing will provide insight into the characteristics of the brain's response to the magnetic pulse and the interaction of the brain's response to a visual stimulus and TMS. These experiments will provide insight to the underlying neural computation within the visual system, afflicted by the TMS pulse. The goals of this research are consistent with the National Plan for Eye and Vision Research of the National Eye Institute. By investigating the underlying circuitry with simulatenous TMS/EEG, we will draw conclusions about normal brain tissue dedicated to visual analysis, which will in turn lead to knowledge that may assist in abnormal diseases of the brain that affect vision. Further, TMS is often used in clinical settings for the treatment of neurological disorders;a better understanding of this method will provide insight into the neural mechanisms affected by this treatment.